Headset loop antenna
A headset has a first and an optional second earpiece 12, 16 respectively coupled to a plug 30 via first and an optional second conductors 14, 20, 18, 22. An antenna loop section 36 has a first loop section 31 at least partially bound to a portion of the first conductor 20, and a second loop section 33 bound to at least a portion of the second conductor 22. Where bound, the first conductor and first loop section may be coaxial or side-by-side. The loop sections include inductors 42,44, and the conductors include ferrite rings 38,40 near the earpieces. A connector 24 mechanically holds the first and second conductors in proximity to one another, and also includes a conductive bridge 34 to electrically couple the first and second loop segments, which may be via a contact connection or a capacitive connection. Audio and RF signals are separated by frequency in a device 50 to which the headset is coupled.
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The present invention generally relates to a loop antennas for radio frequency (RF) signal reception, and is particularly directed to an antenna coupled to a headset that is particularly advantageous for receiving digital video broadcast signals and other broadband signals.
BACKGROUNDPortable electronic devices such as broadcast radio receivers and radiotelephones are continually driven to smaller sizes while offering better performance and more varied features. One engineering challenge in continual size reduction has been improved antenna designs to ensure a reliable and efficient communications interface between the portable device and other entities with which it communicates. Antennas serve to transition an energy signal between circuitry and a wireless channel. The effectiveness of energy transfer between an antenna and its adjacent circuitry is dependent on the terminal impedance of the antenna and that of the adjacent circuit over the desired frequency range.
The directive properties of some antennas, exhibited as a non-uniform radiation pattern, give rise to the concept of antenna gain. Gain is the measure of radiation intensity in a given direction as compared to radiation intensity if the radiation pattern were uniform in all directions. Gain is principally dependent upon the size of an antenna, generally expressed in wavelengths. The gain is measured either on a linear scale or logarithmically in decibels. Larger antennas generally exhibit higher gain. When one or more dimensions of an antenna is significantly larger than a wavelength, its radiation pattern defines a lobe structure, generally with one or more maximums flanked by sidelobes. Maximizing the lobe structure for the intended reception has led to many different configurations for antennas.
A loop antenna has one or more closed conductive pathways, and sometimes a fixed or variable capacitor coupled to the terminals or in series along the conductor of the loop to tune the antenna to resonance. Loop antennas are desirable for their broadband capabilities, a regime in which portable devices are entering using a standard entitled digital video broadcast for handheld devices (DVB-H). Loop antennas are directional, exhibiting radiation patterns with a very large main lobe and a high gain in the direction of that main lobe. By their nature, portable electronic devices are suited to non-directional antennas, since a tower with which the portable device communicates may or may not be aligned with the main lobe of a directional antenna at any given time. Efficiency in a loop antenna is proportional to the area of the loop. In the prior art, a loop antenna no larger than the size of a handheld device results in a very inefficient antenna, which needs additional lossy matching circuits and increases necessary signal processing in the portable device and adds cost while simultaneously reducing battery life.
What is needed in the art is a broadband antenna that is sufficiently small and lightweight for use with a portable device, and that exhibits good reception properties over a broadband frequency range with acceptable efficiency.
SUMMARY OF THE INVENTIONThis invention is in one aspect a headset having a first earpiece, a first conductor that is electrically coupled to the first earpiece, and a conductive loop. The first conductor provides an audio signal to the earpiece. The conductive loop has a first loop segment that is mechanically bound to at least a portion of the first conductor. Preferably, the headset further includes a similar second earpiece and second conductor, and at least a portion of the second loop segment is mechanically bound to at least a portion of a second loop segment of the conductive loop. The conductive loop may be used as a RF receiving antenna and is particularly advantageous for receiving wireless digital video broadcast (DVB-H) signals. Further implementation details are described below.
In another aspect of the invention is a headset that has at least one earpiece coupled to a plug by a conductor, where the improvement includes a conductive loop having a loop segment that is made in one piece with at least a portion of the conductor. Preferably, the headset has a second earpiece coupled to the plug by a second conductor, and a separate second loop segment of the conductive loop is made in one piece with the second conductor.
In yet another aspect of the invention is a method to convert a radiofrequency RF signal to an output signal. The method begins with receiving a RF signal at a loop antenna that is made at least in part in a headset wire, and passing the received RF signal to a portable electronic device via a plug that removably couples the loop antenna to the portable electronic device. Further in accordance with the method, the RF signal is converted in the portable electronic device to an output signal. The output signal may be an audio, video, or audio/video signal, and is preferably sent to a transducer via the plug and headset wire, where at least a portion of the headset wire is mechanically bound to at least a segment of the loop antenna.
In yet another embodiment, the invention is a device for receiving a wireless RF signal, the device having a headset and a receiver. The headset is characterized in that a first earpiece houses a first speaker, a first conductor has a first end coupled to the first earpiece, and a plug coupled to an opposed second end of the first conductor. The plug is for removably coupling to the receiver. Also included in the headset is a loop antenna disposed between the first earpiece and the plug. The receiver is characterized in that it has a receptacle for removably receiving the plug, and has means to convert a RF signal from the loop antenna to an output signal, such as an audio or video signal, that is output to the first conductor.
These and other features, aspects, and advantages of embodiments of the present invention will become apparent with reference to the following description in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for the purposes of illustration and not as a definition of the limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention incorporates a loop antenna into a headset to improve reception in a portable electronic device that provides the signals to the headset. Important to understanding why the invention is effective is that a loop antenna reacts to the magnetic field component of an electromagnetic wave rather than the electric field component. On the other hand, a human body can be approximately deemed as a conductor. In the vicinity of a human body, the electric field is weakened because of an electric image, but the magnetic field is conversely strengthened. Therefore, the antenna characteristics of a loop antenna, when used in the vicinity of a human body are superior to those in the case where the antenna is used in another place. Exploiting this aspect allows the loop antenna of the present invention to deliver enhanced results, as will be quantified in
A headset as used herein is any apparatus intended to be worn on or supported by a user's head that holds at least one speaker or other transducer in the vicinity of the user's ear. Common headsets include an apparatus with speakers in each of two ear cups that are joined by an arcuate support that lies over or behind a persons head (e.g., Bose aviation headset X), and an apparatus with one or two speakers that are fashioned to be inserted into a person's ear canal or supported adjacent to the ear canal by a support arm that overlies the ear adjacent to a person's head (e.g, Nokia headset models HS-10, HDS-3, HS-5). An earpiece is that portion of the headset that houses the speaker or other transducer.
The preferred embodiment of the present invention is shown in perspective view at
The first and second lower conductors 20, 22 are gathered together within a common protective sheath at a bundled conductor section 26 via a y-type coupler 28. The y-type coupler 28 may be merely a mechanical cover, or may preferably also include electronic circuitry such as a microphone for hands-free operation of a radiotelephone to which the headset 10 is electrically coupled and an answer button to answer calls incoming to that radiotelephone. Such features are available on the prior art model HDS-3. The bundled conductor section 26 terminates in a plug 30 or receptacle defining contacts 32, each of which couple either the first 12 or second 16 earpieces electrically to a separate portable device.
In accordance with the present invention, an antenna that includes an antenna loop section 36 and an antenna lead 37 is made a part of the headset. Further details of electrical aspects of the preferred embodiment of the invention are shown schematically in
A first inductor 42 is disposed along the first antenna loop section 31 between the bridge 34 and the coupler 28. Preferably, the first inductor 42 is adjacent the coupler 28 and maximally spaced from the bridge 34 along the first antenna loop section 31. A second inductor 44 is similarly disposed along the second antenna loop section 33, and preferably each inductor 42, 44 defines a like impedance. Preferably the first 31 and second 33 antenna loop segments are coupled to one another and to a conductive antenna lead section 37 at the y-type coupler 28, though in certain embodiments they may join directly at the plug 30. While each of the first 42 and second 44 inductors preferably exhibit like inductance, each inductor 42,44 is a matching element in that it is matched to the desired reception frequency of the loop antenna.
Where the headset 10 includes only one earpiece (e.g., the first earpiece 12), the second upper 18 and lower 22 conductors are not present and the second loop segment 33 is structurally supported by suspension from the first earpiece 12 or preferably from a clip attached to a user's clothing. In such an embodiment, the antenna loop section 36 may be a continuous conductive wire with or without inductors 42,44 as opposed to the above-described loop segments 31, 33 coupled by a distinct conductive bridge 34. Alternatively, such a single-earpiece embodiment may include the conductive bridge 34 to allow sliding, enabling expansion and contraction of the antenna loop.
Two distinct embodiments of the antenna loop section 36 are detailed at
In an alternative embodiment depicted in
Considering again
Preferably, the antenna loop section 36 is coupled to one of the contacts 32 of the plug that also couples with the first 20 or second 22 lower conductor. Alternatively, such as with the embodiment of
Typically, amplifiers disposed within a portable device 50 to which the headset 10 is attached, such as that shown in prior art
Performance data for the inventive loop antenna is next detailed.
The present invention further includes a method to convert radiofrequency signals to audible signals, audible being within the normal hearing range of persons. A RF signal is received at a loop antenna such as the antenna loop section 36 previously described. The RF signal is passed to a portable electronic device such as device 50 via a plug 30 that removably couples the loop antenna to the portable electronic device. Within the portable device, the RF signal is converted to an output signal. While complex, this conversion is well known in the art, such as AM and FM radio receivers, DVB receivers, mobile radiotelephones, and the like. The output signal is then sent to a transducer via the plug 30 and an audio wire such as the first 20 or second 22 conductors previously described. In accordance with the inventive aspects detailed above, at least a portion of the audio wire is mechanically bound to at least a portion of the loop antenna. The method then converts the output signal to an audible signal at the transducer.
Thus, while this invention has been particularly shown and described with respect to certain preferred and alternative embodiments thereof, it will be understood by those skilled in the art that changes in form and details may be made therein without departing from the scope and spirit of these teachings.
Claims
1. A headset comprising:
- an earpiece;
- a conductor coupled to the earpiece; and
- a conductive loop having a loop segment that is mechanically bound to at least a portion of the conductor.
2. The headset of claim 1 wherein the earpiece is a first earpiece, the conductor is a first conductor, and the loop segment is a first loop segment, the headset further comprising:
- a second earpiece and a second conductor coupled to the second earpiece, wherein a second loop segment of the conductive loop is mechanically bound to the second conductor.
3. The headset of claim 2 wherein the conductive loop comprises a conductive bridge that mechanically couples the first and second conductor and that electrically couples the first and second loop segments.
4. The headset of claim 3 wherein the conductive bridge is slideable along at least one of the first and second conductors.
5. The headset of claim 3 wherein the conductive bridge capacitively couples the first and second loop sections.
6. The headset of claim 3 wherein the conductive bridge electrically couples the first and second loop sections via a mechanical connection.
7. The headset of claim 2 further comprising a plug defining a first and second contact, said first conductor electrically coupled to the first contact, said second conductor electrically coupled to said second contact, and the conductive loop electrically coupled to one of the first and second contacts.
8. The headset of claim 2 further comprising a plug defining a first, second and third contact, said first conductor electrically coupled to the first contact, said second conductor electrically coupled to said second contact, and the conductive loop electrically coupled to the third contact.
9. The headset of claim 1 wherein the loop segment comprises at least one matching element.
10. The headset of claim 9 wherein the at least one matching element comprises an inductor.
11. The headset of claim 1 wherein the conductor comprises a ferrite ring.
12. The headset of claim 1 wherein the first conductor and the first loop segment are coaxial with one another at said mechanically bound portion.
13. The headset of claim 1 wherein the first conductor and the first loop segment are disposed within a common insulating sheath at said mechanically bound portion.
14. The headset of claim 1 wherein the conductive loop comprises a loop antenna.
15. In a headset having at least one earpiece coupled to a plug by a conductor, the improvement comprising a conductive loop electrically coupled to the plug, wherein at least a segment of the conductive loop is made in one piece with at least a portion of the conductor.
16. In the headset of claim 15 having a first and a second earpiece, wherein the first earpiece is coupled to the plug by a first connector and the second earpiece is coupled to the plug by a second conductor, the improvement further comprising a first loop segment of the conductive loop being made in one piece with at least a portion of the first conductor, and a second loop segment of the conductive loop being made in one piece with at least a portion of the second conductor.
17. In the headset of claim 16, the improvement further comprising a connector that mechanically couples the first conductor to the second conductor and that electrically couples the first loop segment to the second loop segment.
18. In the headset of claim 17, the improvement further comprising the connector electrically coupling the first loop segment to the second loop segment via a capacitive coupling.
19. In the headset of claim 15, the improvement further comprising at least one inductor disposed along the conductive loop.
20. In the headset of claim 15, the improvement further comprising a ferrite ring disposed along the first conductor between the earpiece and the portion that is mechanically coupled to the conductive loop.
21. In the headset of claim 15, the improvement further comprising the portion of the conductor and the segment of the conductive loop being coaxial.
22. The headset of claim 15 wherein the conductive loop comprises a loop antenna.
23. A method to convert a radiofrequency RF signal to an output signal comprising:
- receiving a RF signal at a loop antenna that is made at least in part in a headset wire;
- passing the RF signal to a portable electronic device via a plug that removably couples the loop antenna to the portable electronic device; and
- converting the RF signal in the portable device to an output signal.
24. The method of claim 23 wherein the output signal comprises an audible signal.
25. The method of claim 23 further comprising:
- sending the output signal to a transducer via the plug and the headset wire, wherein at least a portion of the headset wire is mechanically bound to at least a segment of the loop antenna; and
- converting the output signal to an audible signal at the transducer.
26. The method of claim 23 wherein the output signal comprises a visual signal.
27. A device for receiving a wireless RF signal comprising a headset and a receiver,
- the headset comprising: a first earpiece housing a first speaker, a first conductor having a first end coupled to the first earpiece; a plug coupled to an opposed second end of the first conductor, said plug for removably coupling to the receiver; a loop antenna disposed between the first earpiece and the plug;
- the receiver comprising: a receptacle for removably receiving the plug; and means to convert a RF signal from said loop antenna to an output signal that is output to the first conductor.
28. The device of claim 27 wherein only a portion of the loop antenna is made in one piece with the first conductor.
29. The device of claim 27 wherein the loop antenna is electrically coupled to the receiver through the plug.
30. The device of claim 29 wherein the means to convert comprises at least one capacitor coupled through said receptacle to said loop antenna for separating in a frequency domain the RF signal from the output signal.
31. The device of claim 27 wherein the headset further comprises:
- a second earpiece housing a second speaker,
- a second conductor having a first end coupled to the second earpiece and an opposed second end coupled to the plug;
- wherein the loop antenna has a first portion disposed between the first earpiece and the plug and a second portion disposed between the second earpiece and the plug.
32. The device of claim 31 wherein the loop antenna further comprises a conductive bridge that electrically couples the first and second portions.
33. The device of claim 32 wherein the conductive bridge is slideable along at least one of the first and second conductors.
34. The device of claim 27 wherein the output signal is at least one of an audio signal and a video signal.
Type: Application
Filed: Jun 29, 2004
Publication Date: Dec 29, 2005
Patent Grant number: 7411559
Applicant:
Inventors: Marko Leinonen (Oulu), Marko Autti (Oulu)
Application Number: 10/880,290